#include "ui/ui.h"

#include "debugger/debugger.h"
#include "ui/icons.h"
#include "ui/widgets.h"

#include <glad/gl.h>
#include <imgui.h>
#include <imgui_internal.h>

#include <algorithm>
#include <cfloat>
#include <cmath>
#include <format>
#include <iterator>
#include <string>

#ifndef HSDBG_VERSION
    #define HSDBG_VERSION "dev"
#endif

#ifndef HSDBG_ASSET_DIR
    #define HSDBG_ASSET_DIR ""
#endif

// the preferences window: a category rail on the left and, on the right, that
// category's settings grouped into raised cards of title / description / control
// rows, with theme and accent pickers that show what they pick
namespace Hsdbg
{
    namespace
    {
        constexpr const char* CATEGORIES[] = { "Appearance", "Editor", "Debugger", "About" };
        constexpr const char* CATEGORY_ICONS[] = { ICON_PH_SLIDERS, ICON_PH_FILE_CODE, ICON_PH_BUG, ICON_PH_INFO };
        constexpr const char* CATEGORY_BLURBS[] = {
            "Theme, accent and the shape of the interface",
            "How source is drawn and coloured",
            "How targets launch and step, and the keys that drive them",
            "What this build is made of",
        };

        struct AccentPreset
        {
            const char* name;
            float rgb[3];
        };

        constexpr AccentPreset ACCENTS[] = {
            { "Teal", { 0.302f, 0.714f, 0.769f } },   { "Sky", { 0.357f, 0.659f, 0.961f } },
            { "Indigo", { 0.486f, 0.486f, 0.941f } }, { "Violet", { 0.690f, 0.518f, 0.902f } },
            { "Rose", { 0.886f, 0.478f, 0.604f } },   { "Coral", { 0.941f, 0.541f, 0.365f } },
            { "Amber", { 0.910f, 0.690f, 0.290f } },  { "Mint", { 0.373f, 0.788f, 0.561f } },
        };

        constexpr float CARD_PAD_X = 14.0f;
        constexpr float CARD_PAD_Y = 4.0f;
        constexpr float ROW_PAD_Y = 7.0f;

        // the window, rail and controls grow with the ui scale, since imgui only
        // scales the fonts and would otherwise leave them cramped at 1.5x
        auto ui_scale() -> float
        {
            return ImGui::GetStyle().FontScaleMain;
        }

        auto slider_width() -> float
        {
            return 190.0f * ui_scale();
        }

        auto rgb(const float (&c)[3]) -> ImVec4
        {
            return ImVec4(c[0], c[1], c[2], 1.0f);
        }

        auto u32(const ImVec4& colour) -> ImU32
        {
            return ImGui::ColorConvertFloat4ToU32(colour);
        }

        auto card_rounding() -> float
        {
            return ImGui::GetStyle().FrameRounding + 3.0f;
        }

        // a card is drawn after its rows so it can wrap them: rows go to the upper
        // channel, the card body to the lower one once the height is known
        struct Card
        {
            ImVec2 origin;
            float width = 0.0f;
            int rows = 0;
            ImDrawListSplitter splitter;
        };

        Card g_card;

        auto begin_card() -> void
        {
            ImDrawList* draw = ImGui::GetWindowDrawList();
            g_card.origin = ImGui::GetCursorScreenPos();
            g_card.width = ImGui::GetContentRegionAvail().x;
            g_card.rows = 0;
            g_card.splitter.Split(draw, 2);
            g_card.splitter.SetCurrentChannel(draw, 1);
            ImGui::SetCursorScreenPos(ImVec2(g_card.origin.x + CARD_PAD_X, g_card.origin.y + CARD_PAD_Y));
        }

        auto end_card() -> void
        {
            ImDrawList* draw = ImGui::GetWindowDrawList();
            const ImVec2 end(g_card.origin.x + g_card.width, ImGui::GetCursorScreenPos().y + CARD_PAD_Y);

            g_card.splitter.SetCurrentChannel(draw, 0);
            draw->AddRectFilled(g_card.origin, end, ImGui::GetColorU32(ImGuiCol_FrameBg), card_rounding());
            draw->AddRect(g_card.origin, end, ImGui::GetColorU32(ImGuiCol_Border), card_rounding());
            g_card.splitter.Merge(draw);

            ImGui::SetCursorScreenPos(ImVec2(g_card.origin.x, end.y));
            ImGui::Dummy(ImVec2(g_card.width, 0.0f));
            ImGui::Spacing();
        }

        // one setting: title and dim description on the left, the control pinned
        // to the right edge, both centred on the row; a hairline rules rows apart
        template <typename Control>
        auto setting_row(const char* title, const char* description, float control_width,
                         float control_height, Control&& control) -> void
        {
            const float base = ImGui::GetStyle().FontSizeBase;
            const float title_h = ImGui::GetTextLineHeight();
            const float desc_h = description != nullptr ? std::floor(base * 0.88f) + 3.0f : 0.0f;
            const float row_h = std::max(title_h + desc_h, control_height) + ROW_PAD_Y * 2.0f;
            const float inner = g_card.width - CARD_PAD_X * 2.0f;
            const ImVec2 top(g_card.origin.x + CARD_PAD_X, ImGui::GetCursorScreenPos().y);
            ImDrawList* draw = ImGui::GetWindowDrawList();

            if (g_card.rows > 0)
                draw->AddLine(ImVec2(top.x, top.y - 0.5f), ImVec2(top.x + inner, top.y - 0.5f),
                              ImGui::GetColorU32(ImGuiCol_Border, 0.6f));

            ImGui::SetCursorScreenPos(ImVec2(top.x, top.y + (row_h - title_h - desc_h) * 0.5f));
            ImGui::TextUnformatted(title);
            if (description != nullptr)
            {
                ImGui::SetCursorScreenPos(ImVec2(top.x, ImGui::GetCursorScreenPos().y));
                ImGui::PushFont(nullptr, base * 0.88f);
                ImGui::TextDisabled("%s", description);
                ImGui::PopFont();
            }

            ImGui::SetCursorScreenPos(ImVec2(top.x + inner - control_width, top.y + (row_h - control_height) * 0.5f));
            ImGui::PushID(title);
            control();
            ImGui::PopID();

            ImGui::SetCursorScreenPos(ImVec2(top.x, top.y + row_h));
            ImGui::Dummy(ImVec2(inner, 0.0f));
            ++g_card.rows;
        }

        auto toggle_row(const char* title, const char* description, bool* value) -> bool
        {
            bool changed = false;
            const float h = ImGui::GetFrameHeight() * 0.78f;
            setting_row(title, description, h * 1.8f, h, [&] { changed = Widgets::toggle("##toggle", value); });
            return changed;
        }

        auto slider_row(const char* title, const char* description, float* value, float min, float max,
                        const char* fmt) -> bool
        {
            bool changed = false;
            setting_row(title, description, slider_width(), ImGui::GetFrameHeight(), [&]
            {
                ImGui::SetNextItemWidth(slider_width());
                changed = Widgets::slider_float("##slider", value, min, max, fmt);
            });
            return changed;
        }

        auto color_row(const char* title, const char* description, float (&value)[3]) -> bool
        {
            bool changed = false;
            const float h = ImGui::GetFrameHeight();
            setting_row(title, description, h, h, [&]
            {
                changed = ImGui::ColorEdit3("##colour", value, ImGuiColorEditFlags_NoInputs |
                                                                   ImGuiColorEditFlags_NoAlpha |
                                                                   ImGuiColorEditFlags_NoLabel);
            });
            return changed;
        }

        // a keycap: the key's name in a small sunken box, as on a keyboard legend
        auto key_cap(const char* text) -> void
        {
            const ImGuiStyle& style = ImGui::GetStyle();
            const ImVec2 size = ImGui::CalcTextSize(text);
            const ImVec2 p = ImGui::GetCursorScreenPos();
            const ImVec2 end(p.x + size.x + 16.0f, p.y + ImGui::GetFrameHeight());
            ImDrawList* draw = ImGui::GetWindowDrawList();
            draw->AddRectFilled(p, end, ImGui::GetColorU32(ImGuiCol_WindowBg), style.FrameRounding);
            draw->AddRect(p, end, ImGui::GetColorU32(ImGuiCol_Border), style.FrameRounding);
            draw->AddText(ImVec2(p.x + 8.0f, p.y + style.FramePadding.y), ImGui::GetColorU32(ImGuiCol_Text), text);
            ImGui::Dummy(ImVec2(end.x - p.x, end.y - p.y));
        }

        auto key_row(const char* title, const char* description, const char* key) -> void
        {
            const float width = ImGui::CalcTextSize(key).x + 16.0f;
            setting_row(title, description, width, ImGui::GetFrameHeight(), [&] { key_cap(key); });
        }

        // a read-only fact; a long value is cut from the left and shown whole on hover
        auto value_row(const char* title, std::string value) -> void
        {
            const float inner = g_card.width - CARD_PAD_X * 2.0f;
            const float limit = inner * 0.58f;
            const std::string full = value;
            while (value.size() > 4 && ImGui::CalcTextSize(value.c_str()).x > limit)
                value = "…" + value.substr(4);

            setting_row(title, nullptr, ImGui::CalcTextSize(value.c_str()).x, ImGui::GetTextLineHeight(), [&]
            {
                ImGui::TextDisabled("%s", value.c_str());
                if (value != full && ImGui::IsItemHovered())
                    ImGui::SetTooltip("%s", full.c_str());
            });
        }

        // a theme card: a tiny window in the theme's own palette over its name; the
        // chosen one is ringed in the accent. returns true on click.
        auto theme_card(const ThemeEntry& entry, const Theme& theme, bool selected, ImVec2 size) -> bool
        {
            const ImVec2 p = ImGui::GetCursorScreenPos();
            ImGui::InvisibleButton(entry.id.c_str(), size);
            const bool hovered = ImGui::IsItemHovered();
            const bool clicked = ImGui::IsItemClicked();

            ImDrawList* draw = ImGui::GetWindowDrawList();
            const float r = card_rounding();
            const ImVec2 end(p.x + size.x, p.y + size.y);
            draw->AddRectFilled(p, end, ImGui::GetColorU32(ImGuiCol_FrameBg), r);

            // the mock: title stripe, sidebar, a few lines of "code", an accent pill
            const ImVec2 m0(p.x + 6.0f, p.y + 6.0f);
            const ImVec2 m1(end.x - 6.0f, end.y - 24.0f);
            draw->AddRectFilled(m0, m1, u32(theme.bg), 4.0f);
            draw->AddRectFilled(m0, ImVec2(m1.x, m0.y + 7.0f), u32(theme.bg_low), 4.0f, ImDrawFlags_RoundCornersTop);
            draw->AddRectFilled(ImVec2(m0.x, m0.y + 7.0f), ImVec2(m0.x + 26.0f, m1.y), u32(theme.bg_high), 4.0f,
                                ImDrawFlags_RoundCornersBottomLeft);
            for (int i = 0; i < 3; ++i)
                draw->AddRectFilled(ImVec2(m0.x + 5.0f, m0.y + 13.0f + static_cast<float>(i) * 6.0f),
                                    ImVec2(m0.x + 17.0f + static_cast<float>(i % 2) * 4.0f,
                                           m0.y + 15.0f + static_cast<float>(i) * 6.0f),
                                    u32(theme.text_dim));

            struct Line { float indent, width; ImVec4 colour; };
            const Line lines[] = {
                { 0.0f, 22.0f, theme.syntax_preprocessor }, { 0.0f, 40.0f, theme.syntax_comment },
                { 0.0f, 18.0f, theme.syntax_keyword },      { 8.0f, 36.0f, theme.text },
                { 8.0f, 26.0f, theme.syntax_string },       { 0.0f, 12.0f, theme.text },
            };
            float y = m0.y + 13.0f;
            for (const Line& line : lines)
            {
                if (y + 2.0f > m1.y - 4.0f)
                    break;
                draw->AddRectFilled(ImVec2(m0.x + 32.0f + line.indent, y),
                                    ImVec2(m0.x + 32.0f + line.indent + line.width, y + 2.0f), u32(line.colour));
                y += 6.0f;
            }
            draw->AddRectFilled(ImVec2(m1.x - 24.0f, m1.y - 10.0f), ImVec2(m1.x - 5.0f, m1.y - 4.0f),
                                u32(theme.accent), 3.0f);

            const ImVec2 ts = ImGui::CalcTextSize(entry.name.c_str());
            draw->PushClipRect(ImVec2(p.x + 4.0f, m1.y), ImVec2(end.x - 4.0f, end.y), true);
            draw->AddText(ImVec2(p.x + std::max((size.x - ts.x) * 0.5f, 4.0f), m1.y + (24.0f - ts.y) * 0.5f),
                          ImGui::GetColorU32(selected ? ImGuiCol_Text : ImGuiCol_TextDisabled), entry.name.c_str());
            draw->PopClipRect();

            if (selected)
                draw->AddRect(p, end, u32(Widgets::accent()), r, 0, 2.0f);
            else
                draw->AddRect(p, end, ImGui::GetColorU32(hovered ? ImGuiCol_TextDisabled : ImGuiCol_Border), r);

            return clicked;
        }

        auto same_colour(const float (&a)[3], const float (&b)[3]) -> bool
        {
            return std::abs(a[0] - b[0]) < 0.02f && std::abs(a[1] - b[1]) < 0.02f && std::abs(a[2] - b[2]) < 0.02f;
        }

        auto gl_renderer() -> std::string
        {
            const GLubyte* text = glGetString(GL_RENDERER);
            return text != nullptr ? reinterpret_cast<const char*>(text) : "unknown";
        }
    }

    auto Ui::draw_preferences_window() -> void
    {
        if (!m_show_preferences)
        {
            m_prefs_open_prev = false;
            return;
        }

        // rescan the themes folder when the window opens, so a .toml dropped in
        // while the app is running shows up, and load each palette for its card
        if (!m_prefs_open_prev)
        {
            m_themes = list_themes(themes_directory());
            m_theme_previews.clear();
            std::ranges::transform(m_themes, std::back_inserter(m_theme_previews),
                                   [](const ThemeEntry& entry) { return load_theme(entry.path); });
        }
        m_prefs_open_prev = true;

        const ImGuiViewport* viewport = ImGui::GetMainViewport();
        const ImVec2 center(viewport->WorkPos.x + viewport->WorkSize.x * 0.5f,
                            viewport->WorkPos.y + viewport->WorkSize.y * 0.5f);

        const float scale = ui_scale();
        ImGui::SetNextWindowPos(center, ImGuiCond_Appearing, ImVec2(0.5f, 0.5f));
        ImGui::SetNextWindowSize(ImVec2(860.0f * scale, 600.0f * scale), ImGuiCond_Appearing);
        ImGui::SetNextWindowSizeConstraints(ImVec2(660.0f * scale, 440.0f * scale), ImVec2(FLT_MAX, FLT_MAX));

        if (!ImGui::Begin(ICON_PH_GEAR "  Preferences###preferences", &m_show_preferences,
                          ImGuiWindowFlags_NoDocking | ImGuiWindowFlags_NoCollapse))
        {
            ImGui::End();
            return;
        }

        const float base = ImGui::GetStyle().FontSizeBase;
        bool changed = false;
        bool restyle = false;

        const float footer = ImGui::GetFrameHeightWithSpacing() + ImGui::GetStyle().ItemSpacing.y;

        // the rail: one roomy row per category on the deepest ground
        ImGui::PushStyleColor(ImGuiCol_ChildBg, m_theme.bg_low);
        ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(7.0f, 12.0f));
        ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(6.0f, 8.0f));
        ImGui::BeginChild("##pref_categories", ImVec2(180.0f * scale, -footer), ImGuiChildFlags_AlwaysUseWindowPadding);
        for (int index = 0; index < IM_ARRAYSIZE(CATEGORIES); ++index)
        {
            const std::string label = std::string(CATEGORY_ICONS[index]) + "  " + CATEGORIES[index];
            if (Widgets::selectable_row(label.c_str(), m_preferences_tab == index))
                m_preferences_tab = index;
        }
        ImGui::EndChild();
        ImGui::PopStyleVar(2);
        ImGui::PopStyleColor();

        ImGui::SameLine();

        ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(20.0f, 12.0f));
        ImGui::BeginChild("##pref_content", ImVec2(0.0f, -footer), ImGuiChildFlags_AlwaysUseWindowPadding);
        ImGui::PopStyleVar();

        const int tab = std::clamp(m_preferences_tab, 0, IM_ARRAYSIZE(CATEGORIES) - 1);
        ImGui::PushFont(m_font_strong, base * 1.4f);
        ImGui::TextUnformatted(CATEGORIES[tab]);
        ImGui::PopFont();
        ImGui::TextDisabled("%s", CATEGORY_BLURBS[tab]);
        ImGui::Spacing();

        if (tab == 0)
        {
            Widgets::section_header("Theme", false);

            // dark and light themes in their own rows, four cards across; picking
            // one seeds the accent and syntax colours below and saves
            constexpr int columns = 4;
            const float gap = 8.0f;
            const float card_w = std::floor((ImGui::GetContentRegionAvail().x - gap * (columns - 1)) / columns);
            const ImVec2 card_size(card_w, 72.0f + 20.0f * scale);

            const auto is_light = [](const Theme& theme)
            {
                return 0.299f * theme.bg.x + 0.587f * theme.bg.y + 0.114f * theme.bg.z > 0.5f;
            };

            for (const bool light : { false, true })
            {
                int shown = 0;
                for (size_t index = 0; index < m_themes.size(); ++index)
                {
                    if (is_light(m_theme_previews[index]) != light)
                        continue;

                    if (shown == 0)
                    {
                        ImGui::PushFont(nullptr, base * 0.85f);
                        ImGui::TextDisabled("%s", light ? "Light" : "Dark");
                        ImGui::PopFont();
                    }
                    else if (shown % columns != 0)
                    {
                        ImGui::SameLine(0.0f, gap);
                    }

                    const ThemeEntry& entry = m_themes[index];
                    const bool selected = entry.id == m_preferences.theme;
                    if (theme_card(entry, m_theme_previews[index], selected, card_size) && !selected)
                        select_theme(entry);
                    ++shown;
                }

                if (shown > 0)
                    ImGui::Spacing();
            }
            if (m_themes.empty())
                ImGui::TextDisabled("No themes found in assets/themes");

            ImGui::Spacing();
            Widgets::section_header("Accent", false);

            for (const AccentPreset& preset : ACCENTS)
            {
                const ImVec2 p = ImGui::GetCursorScreenPos();
                ImGui::InvisibleButton(preset.name, ImVec2(26.0f, 26.0f));
                const ImVec2 c(p.x + 13.0f, p.y + 13.0f);
                ImDrawList* draw_list = ImGui::GetWindowDrawList();
                draw_list->AddCircleFilled(c, ImGui::IsItemHovered() ? 11.0f : 10.0f, u32(rgb(preset.rgb)));
                if (same_colour(preset.rgb, m_preferences.accent))
                    draw_list->AddCircle(c, 12.5f, ImGui::GetColorU32(ImGuiCol_Text), 0, 2.0f);
                if (ImGui::IsItemHovered())
                    ImGui::SetTooltip("%s", preset.name);
                if (ImGui::IsItemClicked())
                {
                    std::copy(std::begin(preset.rgb), std::end(preset.rgb), std::begin(m_preferences.accent));
                    changed = true;
                    restyle = true;
                }
                ImGui::SameLine(0.0f, 8.0f);
            }

            if (ImGui::ColorEdit3("##accent_custom", m_preferences.accent,
                                  ImGuiColorEditFlags_NoInputs | ImGuiColorEditFlags_NoAlpha |
                                      ImGuiColorEditFlags_NoLabel))
            {
                changed = true;
                restyle = true;
            }
            ImGui::SameLine();
            ImGui::TextDisabled("Custom");

            ImGui::Spacing();
            Widgets::section_header("Interface", false);
            begin_card();
            changed |= slider_row("UI scale", "Scales every font; text is re-rasterised, so it stays crisp",
                                  &m_preferences.ui_scale, 0.75f, 2.0f, "%.2fx");
            if (slider_row("Corner rounding", "Radius on frames, windows, tabs and buttons",
                           &m_preferences.rounding, 0.0f, 12.0f, "%.0f px"))
            {
                changed = true;
                restyle = true;
            }
            changed |= toggle_row("Show FPS in the status bar", "hsdbg's own frame rate, bottom right",
                                  &m_preferences.show_fps);
            end_card();

            Widgets::section_header("Layout", false);
            begin_card();
            {
                const float w = ImGui::CalcTextSize("Reset layout").x + ImGui::GetStyle().FramePadding.x * 2.0f;
                setting_row("Window layout", "Put every panel back where a fresh install has it", w,
                            ImGui::GetFrameHeight(), [&]
                {
                    if (ImGui::Button("Reset layout"))
                        m_layout_built = false;
                });
            }
            end_card();

            Widgets::section_header("Mascot", false);
            begin_card();
            changed |= toggle_row("Show the crying pepe", "He lives in the toolbar and means well",
                                  &m_preferences.show_mascot);
            ImGui::BeginDisabled(!m_preferences.show_mascot);
            changed |= slider_row("Pepe size", "As a multiple of a toolbar button", &m_preferences.mascot_scale,
                                  1.0f, 3.0f, "%.1fx");
            ImGui::EndDisabled();
            end_card();
        }
        else if (tab == 1)
        {
            Widgets::section_header("Font", false);
            begin_card();
            changed |= slider_row("Source font size", "Cmd/Ctrl + scroll over the source zooms it too; Cmd/Ctrl + 0 resets",
                                  &m_preferences.source_font_size, 9.0f, 32.0f, "%.0f px");
            end_card();

            Widgets::section_header("Source view", false);
            begin_card();
            changed |= toggle_row("Syntax highlighting", "Colour keywords, types, strings and the rest",
                                  &m_preferences.syntax_highlighting);
            changed |= toggle_row("Show line numbers", nullptr, &m_preferences.show_line_numbers);
            changed |= toggle_row("Highlight the current line", "Tint the line execution has stopped on",
                                  &m_preferences.highlight_current_line);
            end_card();

            Widgets::section_header("Syntax colours", false);

            // a live sample in the source face and size, coloured as the source
            // view would colour it right now
            {
                struct Token { const char* text; int kind; };
                const Token sample[][6] = {
                    { { "#include", 6 }, { " ", 0 }, { "<cstdio>", 3 }, { nullptr, 0 } },
                    { { "// the answer, as a function", 5 }, { nullptr, 0 } },
                    { { "auto", 2 }, { " answer(", 0 }, { "int", 2 }, { " base) -> ", 0 }, { "int", 2 }, { nullptr, 0 } },
                    { { "{", 0 }, { nullptr, 0 } },
                    { { "    ", 0 }, { "const", 1 }, { " ", 0 }, { "char", 2 }, { "* text = ", 0 }, { "\"hello\";", 3 } },
                    { { "    ", 0 }, { "return", 1 }, { " base * ", 0 }, { "42", 4 }, { ";", 0 }, { nullptr, 0 } },
                    { { "}", 0 }, { nullptr, 0 } },
                };
                const float (*colours[])[3] = {
                    nullptr, &m_preferences.color_keyword, &m_preferences.color_type, &m_preferences.color_string,
                    &m_preferences.color_number, &m_preferences.color_comment, &m_preferences.color_preprocessor,
                };

                ImGui::PushFont(m_font_mono, m_preferences.source_font_size);
                const float line_h = ImGui::GetTextLineHeight() + 4.0f;
                const float pad = 12.0f;
                const ImVec2 p = ImGui::GetCursorScreenPos();
                const ImVec2 size(ImGui::GetContentRegionAvail().x, line_h * IM_ARRAYSIZE(sample) + pad * 2.0f);
                ImDrawList* draw_list = ImGui::GetWindowDrawList();
                draw_list->AddRectFilled(p, ImVec2(p.x + size.x, p.y + size.y), u32(m_theme.bg_low), card_rounding());
                draw_list->AddRect(p, ImVec2(p.x + size.x, p.y + size.y), ImGui::GetColorU32(ImGuiCol_Border), card_rounding());

                const int current = 5;
                if (m_preferences.highlight_current_line)
                {
                    const float y = p.y + pad + line_h * current - 2.0f;
                    draw_list->AddRectFilled(ImVec2(p.x + 1.0f, y), ImVec2(p.x + size.x - 1.0f, y + line_h),
                                        u32(rgb(m_preferences.color_current_line)));
                    draw_list->AddRectFilled(ImVec2(p.x + 1.0f, y), ImVec2(p.x + 4.0f, y + line_h), u32(Widgets::accent()));
                }

                for (int line = 0; line < IM_ARRAYSIZE(sample); ++line)
                {
                    float x = p.x + pad + 8.0f;
                    const float y = p.y + pad + line_h * static_cast<float>(line);
                    for (const Token& token : sample[line])
                    {
                        if (token.text == nullptr)
                            break;
                        const bool plain = token.kind == 0 || !m_preferences.syntax_highlighting;
                        const ImU32 colour = plain ? ImGui::GetColorU32(ImGuiCol_Text) : u32(rgb(*colours[token.kind]));
                        draw_list->AddText(ImVec2(x, y), colour, token.text);
                        x += ImGui::CalcTextSize(token.text).x;
                    }
                }
                ImGui::PopFont();
                ImGui::Dummy(size);
                ImGui::Spacing();
            }

            begin_card();
            ImGui::BeginDisabled(!m_preferences.syntax_highlighting);
            changed |= color_row("Keyword", "const, return, if, while…", m_preferences.color_keyword);
            changed |= color_row("Type", "int, auto, char, size_t…", m_preferences.color_type);
            changed |= color_row("String", "String and character literals, includes", m_preferences.color_string);
            changed |= color_row("Number", nullptr, m_preferences.color_number);
            changed |= color_row("Comment", nullptr, m_preferences.color_comment);
            changed |= color_row("Preprocessor", "#include, #define and friends", m_preferences.color_preprocessor);
            ImGui::EndDisabled();
            changed |= color_row("Current line", "Behind the line execution has stopped on", m_preferences.color_current_line);
            end_card();
        }
        else if (tab == 2)
        {
            Widgets::section_header("Launching", false);
            begin_card();
            changed |= toggle_row("Break at entry point", "Stop on the very first instruction instead of running to your breakpoints",
                                  &m_preferences.stop_at_entry);
            end_card();

            Widgets::section_header("Stepping", false);
            begin_card();
            {
                static const char* const step_modes[] = { "Line", "Instruction" };
                const int current_mode = m_preferences.step_by_instruction ? 1 : 0;
                int next_mode = current_mode;
                setting_row("Step granularity", "What Step Over and Step Into advance by", 
                            Widgets::segmented_width(step_modes, 2), ImGui::GetFrameHeight(), [&]
                {
                    next_mode = Widgets::segmented("##step_mode", step_modes, 2, current_mode);
                });
                if (next_mode != current_mode)
                {
                    m_preferences.step_by_instruction = next_mode == 1;
                    changed = true;
                }
            }
            end_card();

            Widgets::section_header("Keys", false);
            begin_card();
            key_row("Continue, or run a loaded target", nullptr, "F5");
            key_row("Step Over", nullptr, "F10");
            key_row("Step Into", nullptr, "F11");
            key_row("Step Out", nullptr, "Shift + F11");
            key_row("Command palette", "Files, symbols and every command, fuzzy-matched", "Cmd/Ctrl + K");
            key_row("Zoom the source", "Over the source view", "Cmd/Ctrl + scroll");
            end_card();
        }
        else
        {
            ImGui::PushFont(m_font_strong, base * 2.0f);
            ImGui::TextUnformatted("hsdbg");
            ImGui::PopFont();
            ImGui::SameLine(0.0f, 10.0f);
            ImGui::AlignTextToFramePadding();
            Widgets::chip(HSDBG_VERSION, u32(Widgets::accent()));
            ImGui::TextDisabled("A GUI debugger for C and C++. LLDB does the debugging; this is the ui.");
            ImGui::Spacing();

            Widgets::section_header("Build", false);
            begin_card();
            value_row("LLDB", Debugger::backend_version());
            value_row("Dear ImGui", IMGUI_VERSION);
            value_row("OpenGL", gl_renderer());
            value_row("Fonts", "Nunito, JetBrains Mono, Phosphor");
            end_card();

            Widgets::section_header("Paths", false);
            begin_card();
            value_row("Assets", HSDBG_ASSET_DIR);
            value_row("Preferences", m_preferences_path.string());
            value_row("Layout", ImGui::GetIO().IniFilename != nullptr ? ImGui::GetIO().IniFilename : "none");
            end_card();
        }

        ImGui::EndChild();

        ImGui::Separator();

        if (ImGui::Button("Reset to defaults"))
        {
            m_preferences = Preferences{};
            // realign the neutral palette with the default theme so the reset
            // accent does not sit on top of the previously loaded theme's levels
            load_selected_theme(false);
            changed = true;
            restyle = true;
        }

        ImGui::SameLine();
        ImGui::AlignTextToFramePadding();
        ImGui::TextDisabled("Saved to %s as you change things", m_preferences_path.filename().string().c_str());

        if (changed)
            save_preferences(m_preferences_path, m_preferences);

        if (restyle)
            m_restyle_pending = true;

        ImGui::End();
    }
}